Shirts with button-down collars are not dress shirts.

This phenomenon, known as salaula, explains why so few of the women along the road now wear chitenges, and also why a man on a bicycle too poor to have shoes may be wearing a formal dress shirt.

After his visit to the store in August, Mr. Hevey left with a suit, three sport coats, five shirts, two pairs of jeans and seven pairs of khakis.